migration: new postcopy-pause state

Introducing a new state "postcopy-paused", which can be used when the
postcopy migration is paused. It is targeted for postcopy network
failure recovery.

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20180502104740.12123-3-peterx@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>

migration/migration.c

@@ -574,6 +574,7 @@ static bool migration_is_setup_or_active(int state)
     switch (state) {
     case MIGRATION_STATUS_ACTIVE:
     case MIGRATION_STATUS_POSTCOPY_ACTIVE:
+    case MIGRATION_STATUS_POSTCOPY_PAUSED:
     case MIGRATION_STATUS_SETUP:
     case MIGRATION_STATUS_PRE_SWITCHOVER:
     case MIGRATION_STATUS_DEVICE:
@@ -654,6 +655,7 @@ static void fill_source_migration_info(MigrationInfo *info)
     case MIGRATION_STATUS_POSTCOPY_ACTIVE:
     case MIGRATION_STATUS_PRE_SWITCHOVER:
     case MIGRATION_STATUS_DEVICE:
+    case MIGRATION_STATUS_POSTCOPY_PAUSED:
          /* TODO add some postcopy stats */
         info->has_status = true;
         info->has_total_time = true;

qapi/migration.json

@@ -89,6 +89,8 @@
 #
 # @postcopy-active: like active, but now in postcopy mode. (since 2.5)
 #
+# @postcopy-paused: during postcopy but paused. (since 2.13)
+#
 # @completed: migration is finished.
 #
 # @failed: some error occurred during migration process.
@@ -106,7 +108,8 @@
 ##
 { 'enum': 'MigrationStatus',
   'data': [ 'none', 'setup', 'cancelling', 'cancelled',
-            'active', 'postcopy-active', 'completed', 'failed', 'colo',
+            'active', 'postcopy-active', 'postcopy-paused',
+            'completed', 'failed', 'colo',
             'pre-switchover', 'device' ] }
 
 ##